code: def test_one_node_graph():
      """Second order centrality: single node"""
      G = nx.Graph()
      G.add_node(0)
      G.add_edge(0, 0)
      assert nx.second_order_centrality(G)[0] == 0
  
file_path: networkx/networkx/algorithms/centrality/tests/test_second_order_centrality.py
imports: import pytest
  import networkx
label_desc: Use image node_id 5 for calling a global function with example usage: test_one_node_graph() without return types